In an inkjet printer head of a shear mode and shear wall system, a sidewall common to pressure chambers adjacent to each other is driven. Therefore, ink may not be able to be simultaneously ejected from the adjacent pressure chambers. Further, even if sidewalls of every other pressure chambers are simultaneously driven, it is likely that the ink is ejected by mistake from pressure chambers present among the pressure chambers from which the ink is ejected.
In order to prevent the mis-ejection of the ink, sidewalls of at least every two other pressure chambers are simultaneously driven (three-division driving). If the three-division driving is performed, a driving frequency of an inkjet head is delayed. Therefore, in order to improve the driving frequency, pressure chambers for ejecting the ink and dummy chambers for not ejecting the ink are sometimes alternately provided. In the pressure chambers, orifices from which the supplied ink is ejected are opened. On the other hand, the dummy chambers are closed without being provided with orifices. The ink is only filled in the dummy chambers.
Since the pressure chambers and the dummy chambers are alternately arranged, even if sidewalls of driving elements forming the pressure chambers are deformed in a shear mode, the mis-ejection of the ink is prevented. This makes it possible to simultaneously eject the ink from the pressure chambers and improve the driving frequency of the inkjet head.
Further, pressure chambers and air chambers containing the air without being provided with orifices are sometimes alternately provided. This also prevents the mis-ejection of the ink and makes it possible to simultaneously eject the ink from the pressure chambers.
For example, since the orifices are not provided in the dummy chambers, it is likely that the ink is not sufficiently filled in the dummy chambers and the air accumulates in the dummy chambers. If amounts of the air accumulating in the dummy chambers are different from one another, crosstalk amounts of the pressure chambers are different. Since the supplied ink accumulates in the dummy chambers, it is likely that the temperature of the ink in the dummy chambers rises and affects the ink ejection from the pressure chambers.
If the air chambers are provided, a structure for preventing the ink from entering the air chambers is necessary. Therefore, the structure of the inkjet head is complicated and costs and labor and time for manufacturing the inkjet head increase.